Tunnel fan



July 18, 1939. E. L. ANDERSON `2,166,276

TUNNEL FAN 'V Filed Oct. 6, 1937 5 Sheets-Sheet l July 18, 1939. E. 1ANDERSON 2,166,276

TUNNEL FAN Filed Oct. 6, 1937 5 Sheets-Sheet 2 EDWARD LAND son, BY w MJuly 18, 1939. E. l.. ANDERSON TUNNEL FAH Filed Oct. 6. 193'? 5Sheets-Sheet 3 July 18, 1939. E4 L. ANDERSON 4 t e e h S S t e e h s 5TUNNEL FAN Filed Oct. 6, 1937 TUNNEL FAN Filed Oct. 6, 1937 5Sheets-Sheet 5 JWM/W EDWARD [ANDERSON Patented July 18, 1939 PATENTOFFICE TUNNEL FAN Edward L. Anderson, Wayne County, Mich., assignor toAmerican Blower Corporation, Dctroit, Mich., a corporation of DelawareApplication October 6, 1937, Serial No. 167,62

17 Claims. (Cl. 23o-114) My invention relates to fans.

It is the object of this invention to provide a fan in which the changein direction of the flow oi the air into the fan is achieved by use ofleast velocity and the lowest pressure loss.

It is a further object to provide a method of introducing air at therequired angle and preventing swirls or readjustment of the angularvelocity of the air just prior to entering the wheel of the fan.

It is a further object of this invention to provide means by which theangular direction of the air is altered most rapidly at the largest areawhere the air enters, and the angular change of direction of the airfrom this point on becomes less until it is substantially parallel tothe shaft at the point of greatest restriction of the section of theinlet of the fan. This line approaches a hyperbolic curve thus changingthe angular direction of the air flow at the point of leastvelocity andconsequently the point of least loss, the angular change being less asthe area is decreased.

It is a further object to provide inlet vanes of substantially flatsheets having the leaving edges radial to the center line of the shaft,this leaving edge being approximately at the point of least area of theinlet cone. The air entry edge is arranged on an angle dependent uponthe amount of effort required by the entering vane. It is nonparallel tothe axis of the shaft, this line being determined purely by the angle ofthe blade as the inlet blade is rotated around the leaving edge, whichis radial to the shaft.

The reason for the use of inlet vanes is that the characteristics of thefan may be altered by rotating the air in the direction of the wheelrotation by the use of vanes thus changing the relation of the shaftrevolutions per minute to a given pressure. The greater this angle, theless the pressure for a givenspeed. It is possible to change thedirection of the air entry up to and including an angle of 30 degreeswithout aifecting the efliciency of the fan. Up to 30 degrees, theemciency in that part of the curve where the pressures are fairly high,is greater than that of a fan having no such inlet vanes.

It is a further object to provide a. fan casing having a scroll which isnot a true volute.

Referring to the drawings:

Figure 1 is a diagrammatic vieW of the scroll casing of the fan showingthe points of description of the scroll. 'I'he inlet blades of the fanand the fan are not indicated for the purpose of clarity.

Figure 2 is a front elevation of the inlet side of the i'an with a shaftin section.

Figure 3 is a section on the line 3-3 of Figure 2.

Figure 4 is a view of Figure 1 looking from 6 the left end of Figure 1.

Figure 5 is a plan view of one of the air entry blades.

Figure 6 is an end elevation thereof, showing the angle extension of theblade, which is used to attach it to the sleeve about.the axle of thefan.

Figure '7 is a diagrammatic view showing a curve illustrating thefeatures of advantage of the fan of this invention.

Referring to the drawings in detail, I designates an inlet opening of ascroll casing having side Walls 2 and 3. 'This casing has a volute wall4. The angular advance or increase of the scroll is lnot a true volute.It varies in more than two of its points out of the true volute circle.5 represents the center of the inlet opening I. The points 6, 1, 8, 9and I0 are points about which portions of the scroll are described. IIdesignates the discharge passageway, and I2 designates the dischargeopening for the air that is discharged.

The air inlet opening I is provided with an air inlet passageway havingtwo cones of different angles. The angular direction of the air is a1-tered more rapidly at the larger area dened by the conical portion I3.This is the entry area. The angular change of direction from this pointon becomes less until it is vertically parallel to the shaft at thepoint of greatest restriction at the inlet chamber, such as at I4.Intermediate I3 and I4 is the section I5 which is arranged at a lesserangle than the section I3. This line of flow `which approaches ahyperbolic curve thus changes the angular direcetion of air flow at thepoint of least velocity and consequently the point of least loss, theangular change being less at the area is decreased.

The inner end of this conical inlet having the several sectionsdescribed, is provided with an inwardly aring section I6, which overlapsthe vane shroud I1 to form a reentry air space to provide the maximumflow over the outer ends of the fan blades I9. These blades are carriedupon the back disc 20, which is in turn mounted upon the hub 2I of thedriving shaft 22.

In this inlet passageway composed of these several sections are aplurality of guide vanes 23, the outer ends of which are fastened,preferably by welding, to the inner side of the inlet passagewaysections I3, I4 and I5. The axle end 'I'he edge of the blade 2l thatengages the conical inlet is designated 2l. The air entering edge is 2l.and the leaving edge is I.. This entering edge 2l projects beyond theconical inlet as at Il and. has outer cut-olends Il. A protecting screenIl is suspended over the inlet.

It will thus be seen that the inlet vanes are comprised of flat sheets2l having leaving edge Il radial to the center line of the shaft 22.This leaving edge is approximately the point of the least area of theinlet cone. The air entering edge 2l is on an angle dependent upon theamount of eil'ort required for the vane 23. It is non-parallel to theaxis of the shaft. This line is determined purely by the angle of theblade as the inlet blade is rotated around the leaving edge l0 which isradial to the shaft 22.

The change in direction in the flow of the air is therefore achieved atthe point of least velocity and lowest pressure loss. The leaving edgeof the blade acts purely as a means of introducing air at the requiredangle into the fan, and to prevent swirls or readjustment of the angularvelocity just prior to entering the fan wheel. The characteristics ofthe fan may be 'altered by rotating the air in the vdirection of thewheel rotation. by use of these vanes 23, thus changing the relation ofthe shaft revolutions per minute to a given pressure. The greater thisangle, the less the pressure for a given speed. It is possibleto changethe direction of air entry up to and including an angle of 30 degreeswithout eiecting the emciency of the fan. The efficiency in the curveWhere the pressures are fairly high, is greater than that of a fanhaving no such inlet vanes.

With reference to the diagram or curve of Figure 7, the full linesindicate the performance of the fan only without the inlet vanes. Thedotted lines indicate the performance with the inlet vanes of thisinvention. It will be seen that the.

characteristics of the fan are altered considerably by rotating the airin the direction of the wheel rotation by use of the vanes, thuschanging the relationship of shaft R. P. M. to a given pressure. Thegreater this angle, the less the pressure for a given period. It ispossible to change the direction of air entry up to and including anangle of thirty degrees Without affecting the efficiency of the fan withthe result that where the pressures are fairly high, the eillciency isgreater than that of a fan having no such inlet vanes, as shown inFigure 7.

Method of operation The method of operation of this fan is as follows.By the use of successive cones of different angularity in inlet followedby a rolled section the angular direction of the air is altered mostrapidly at the area of largest cross section of the body of the enteringair. The angular change of direction of the air from this point onbecomes less until it is virtually parallel to the shaft at the point ofgreatest restriction of the rolled section. This line approaches ahyperbolic curve. Thus the changes of the angular direction of the airflow occur at the point or area of least velocity, and consequently thepoint of least loss because the angular change of direction of the airbecomes less as the cross sectional area of the body of the air isdecreased.

With reference to the inlet vanes and their cooperation in thiscombination, the air entering edge is located on an angle depending uponthe amount of effort required for the vane. The non-parallel dispositionof the edge Vto the axis of the shaft of the fan is determined by theangle of the blade as the inlet blade is rotated around the leavingedge, which is radial tothe shaft. The change in direction of the ilowof the air is therefore achieved at the pointof least velocity andlowest pressure loss. "The leaving edge of the blade acts as a means'ofintroducing the air at the required angle to prevent swirls orreadiustment of the angular velocity justprior to entering the wheel.The reason for the use on the inlet vanes is that the characteristics ofthe fan may be altered considerably by rotating the air in the directionof the wheel rotation by the use of the vanes, thus changing therelations oi' shaft R. P. M. to a given pressure. 'I'he greater thisangle, the less the pressure for a given speed. It is possible to changethe direction of the air entry up to and including an angle of 30degrees without affecting the eillciency of the fan. Up to 30 degrees,the efficiency in that part of the curve where the pressures are fairlyhigh, is greater than that of a fan having no such inlet vanes. Thepressure of a scroll that is not a true volute improves the efficiencyof this combination.

It will be understood that I desire to comprehend within my inventionsuch modifications as may be clearly embraced within the claims andscope of my invention.

Having thus fully described my invention, what I claim as new and desireto secure by Letters Patent, is:

1. In a fan, the combination of a fan casing, a fan rotor and aplurality of flat air inlet vanes the maximum dimension of which is atright angles to the fan rotor axis and characterized by having theleaving edge thereof radial to the axis of the rotor, and the entry edgeof the fan non-radial thereto, each of said vanes comprising ilatsheets, except adjacent the points of attachment of the inner and outeredges thereof.

2. In combination in a fan of a casing. a rotor mounted on a shaft, aninlet passageway extending into said casing and a plurality of fiatinlet vanes the maximum dimension of which is at right angles to the fanrotor axis, the entry edge of which is non-radial to said shaft and theleaving edge of which is radial to the shaft.

3. In combination in a fan of a casing, a rotor mounted on a shaft, aninlet passageway extending into said casing and a plurality of flatinlet vanes the maximum dimension of which is at right angles to the fanrotor axis, the entry edge of which is non-radial to said shaft and theleaving edge of which is radial to the shaft, the inner ends of saidvanes being bent at right angles to the main portion of the vane to forma means of supporting said vane with its edges as described.

4. In combination in a fan having an inlet passageway of a plurality offlat sheet inlet vanes the maximum dimension of which is at right anglesto the fan rotor axis with the entering edge thereof non-parallel to theaxis of the shaft and with the leaving edge radial to the shaft, andmeans for positioning the vanes at approximately the point of least areaand minimum cross section of the inlet passageway.

5. In combination, in a fan of a fan housing having an inlet passagewayand a rotor within said casing having a shaft disposed on the axis ofsaid inlet passageway, a central sleeve surrounding said shaft, aplurality of flat inlet vanes the maximum dimension of which is at4righi: angles to the fan rotor axis and disposed at an angle to theaxis of the shaft so that the faces of the vanes are presented outwardlyin the direction of the entering air, and with the entering edges ofsaid vanes arranged non-radially of said shaft and the leaving edges ofthe vanes arranged radially of the shaft adjacent the fan rotor.

6. In combination, in a fan of a fan housing having an inlet passagewayand a rotor within said casing having a shaft disposed on the axis ofsaid inlet passageway, a plurality of fiat inlet vanes the maximumdimension of which is at right angles to the fan rotor axis and disposedat an angle to the axis of the shaft so that the faces of the vanes arepresented outwardly in the direction of the entering air, and with theentering edges of said vanes arranged non-radially of said shaft and theleaving edges of the vanes arranged radially of the shaft adjacent thefan rotor, and means for supporting the inner ends of said vanescomprising angular portions thereof connected to a central sleevemounted around said shaft and a sleeve so mounted in spaced relationshipwith respect to `said shaft adapted to support the inner ends of saidvanes.

7. In combination, a fan casing, a rotor therein having a shaftextending through an inlet passageway and means for forming an inletpassageway comprising a generally conical inlet body consisting of twoflat conical sections of different angularity and a rolled arcuatesection so arranged that the angle direction of the air is altered mostrapidly at the largest area at the entry point and the angular change ofthe direction of air from this point inwardly becomes less until it isvirtually parallel to the shaft at the point of greatest restriction ofthe rolled section of the inlet'passageway.

8. In combination, a fan casing, a rotor therein having a shaftextending through an inlet passageway and means for forming an inletpassageway comprising a generally conical inlet body consisting of twoflat conical sections and a rolled arcuate section so arranged that theangle direction of the air is altered most rapidly at the largest areaat the entry point and the angular change of the direction of air fromthis point inwardly becomes less until it is virtually parallel to theshaft at the point of greatest restriction of the rolled section of theinlet passageway, and a plurality of flat inlet vanes the maximumdimension of which is at right angles to the fany rot-or axis andangularly disposedwith` respect "tosaid shaft having their outer, edgesmounted on the inside of said inlet passageway andtheir inner edgesconnected to one another about said shaft in such a manner that theentering edge of the vanes is non-radial to the shaft and the leavingedges are radial to the shaft.

9. In combination, in a fan of an inlet passageway comprising .ilatsections of different decreasing angularlty with respect to the. axis ofthe passageway and an inner arcuate section whose maximum inner diameteris greater than the minimum diameter of the inlet passageway.

10. In combination, in a fan of an inlet passageway comprising fiatsections of decreasing angularity with respect to the axis of the pas--sageway and an inner arcuate section whose maximum inner diameter isgreater than the minimum diameter of the inlet passageway, and aplurality of fiat vanes mounted in and upon said passageway with theside thereof facing outwardly, the entry edges thereof being arrangednon-radially of the axis of the passagewayand the leaving edges thereofbeing arranged radially thereof.

11. In combination, in a fan of an inlet passageway comprising flatsections of decreasing angularity with respect to the axis of thepassageway and an inner arcuate section whose maximum inner diameter isgreater thanthe minimum diameter of the inlet passageway, and aplurality of fiat vanes mounted in and upon said passageway with theside thereof facing outwardly, the entry edges thereof being arrangednon-radially of the axis of the passageway and the leaving edges thereofbeing arranged radially thereof, and angularly disposed means on theinner ends of said vanes for attaching them to a sleeve, and a sleevefor supporting said inner ends arranged axially of the axis of saidpassageway.

12. In combination, a fan housing, a rotor mounted therein having ashaft projecting through, an entry opening in said housing, a generallyconical inlet passageway comprising a series of flat sectionsofdifferent decreasing angularity with respect to the axis of said shaftand an inner arcuate section whose maximum inner diameter is greaterthan the minimum diameter of the inlet passageway arranged inoverlapping spaced relationship with respect to the rotor.

13. In combination, a fan housing, a rotor mounted therein having ashaft projecting through, an entry opening in said housing, a generallyconical inlet passageway comprising a series of fiat sections ofdecreasing angularity with respect to the axis of said shaft and aninner arcuate section whose maximum inner diameter is greater than theminimum diameter of the inlet passageway arranged in overlapping spacedrelationship with respect to the rotor, and a plurality of flat inletvanes having their faces disposed at an angle to the entering air, saidvanes being located with their outer ends engaging inlet passageway andinlet edges non-radial to said shaft and their leaving edges radial tosaid shaft.

14. In combination in a fan, a casing, a rotor therein, an inletpassageway restricted between its ends and guide vanes in saidpassageway',A said passageway being of such angular section with respectto the axis of the passageway that the angular direction of the air isaltered most rapidly at the maximum area of the passageway at the` entrypoint and the angular direction of air inwardly becomes less as guidedby the passageway until it is virtually parallel to the rotor shaft atthe point of minimum diameter of the 'inlet passageway, and said vanesbeing so arranged that they are presented at an angle of not more thanapproximately 30 degrees with respect to the direction of entry of theair, said vanes having their entering edges non-radial to the rotorshaft and their leaving edges radial thereto.

15. In combination, a fan casing, a rotor therein and an inlet conicalpassageway restricted between its ends having conical sections ofdifferent angularity and a plurality of inlet vanes angularly disposedwith respect to the direction of the entry of air with their enteringedges nonradial and their leaving edges radial to the axis of the rotorshaft.

18. In combination, a tan casing. a rotor therein and an inletconicalpassageway restricted between lts ends having conical sections o!diiterent angularity and a plurality oi inlet vancs anguiarly disposedwith respect to the direction of the entry of air with their enteringedges nonradial and their leaving edges radial to the axis o! the rotorshaft, said fan having a scroll casing that is not a true volute.

17. In combination, a scroll casing, a conical inlet passagewayrestricted between its ends having a plurality of diiIerent angularsectionalV areas and a plurality of inlet vanes angularly disposed withrespect to the incoming air with their entering edges non-radial andtheir leaving edges radial to the axis of the inlet passageway.

EDWARD L. ANDERSON.

